[Xen-changelog] [xen staging] VT-d: don't pass bridge devices to domain_context_mapping_one()

[patchbot@xxxxxxx]

commit a4d457fd59f4ebfb524aec82cb6a3030087914ca
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Jan 22 16:39:58 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jan 22 16:39:58 2020 +0100

    VT-d: don't pass bridge devices to domain_context_mapping_one()
    
    When passed a non-NULL pdev, the function does an owner check when it
    finds an already existing context mapping. Bridges, however, don't get
    passed through to guests, and hence their owner is always going to be
    Dom0, leading to the assigment of all but one of the function of multi-
    function PCI devices behind bridges to fail.
    
    Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 0411c5a7f0..3d60976dd5 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1493,18 +1493,28 @@ static int domain_context_mapping(struct domain 
*domain, u8 devfn,
         if ( find_upstream_bridge(seg, &bus, &devfn, &secbus) < 1 )
             break;
 
+        /*
+         * Mapping a bridge should, if anything, pass the struct pci_dev of
+         * that bridge. Since bridges don't normally get assigned to guests,
+         * their owner would be the wrong one. Pass NULL instead.
+         */
         ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn,
-                                         pci_get_pdev(seg, bus, devfn));
+                                         NULL);
 
         /*
          * Devices behind PCIe-to-PCI/PCIx bridge may generate different
          * requester-id. It may originate from devfn=0 on the secondary bus
          * behind the bridge. Map that id as well if we didn't already.
+         *
+         * Somewhat similar as for bridges, we don't want to pass a struct
+         * pci_dev here - there may not even exist one for this (secbus,0,0)
+         * tuple. If there is one, without properly working device groups it
+         * may again not have the correct owner.
          */
         if ( !ret && pdev_type(seg, bus, devfn) == DEV_TYPE_PCIe2PCI_BRIDGE &&
              (secbus != pdev->bus || pdev->devfn != 0) )
             ret = domain_context_mapping_one(domain, drhd->iommu, secbus, 0,
-                                             pci_get_pdev(seg, secbus, 0));
+                                             NULL);
 
         break;
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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